Embodiments of the present invention relate to integrated circuit (IC) package and printed circuit board (PCB) technologies. More particularly, the embodiments relate to lossy material inserts located in IC packages and PCB's.
Circuit designers continually pursue electronic circuits that run faster. Examples of such circuits are those with shorter rise times and fall times. These circuits may have an increased signal frequency spectrum that can be, for example, between 40 GHz and 50 GHz. Unfortunately, the increased frequency may result in increased levels of undesirable electronic noise, such as simultaneous switching noise and package resonance. This electronic noise can adversely affect signal integrity within the semiconductor substrate packaging or PCB.
Various mechanisms can cause electronic noise. For example, simultaneous switching noise can be caused when electronic switches (e.g., transistors) turn on or off simultaneously. The switching action may induce an electronic wave (e.g., propagation wave). The wave propagates to the edge of the semiconductor package and then reflects off the edge. This wave reflection results in a wave that resonates within the package, thereby creating a resonant circuit with a resonant frequency. The resonant frequency may interfere with other frequencies in the circuit. Furthermore, large input impedances may develop around the resonant frequency. These impedances can exacerbate noise issues such as package resonance. Thus, propagation wave excitation is one mechanism by which undesirable electronic noise (e.g., simultaneous switching noise and package resonance) can be created and adversely affect signal integrity.
Traditionally, designers have used decoupling capacitors to attempt to manage electronic noise such as package resonance. However, decoupling capacitors merely shift package resonance without reducing the resonance to any large degree. In addition, the capacitors can be expensive to implement and take up valuable space on the substrate (e.g., semiconductor package substrate, PCB). Thus, the use of decoupling capacitors to solve noise issues, such as simultaneous switching noise and package resonance, is less than ideal.